# How do you find the product of (d-1)(5d-4)?

Dec 21, 2016

$= 5 {d}^{2} - 9 d + 4$

#### Explanation:

We have 2 factors which have to be multiplied. Each part of the first bracket has to be multiplied by each part of the second bracket. This is sometimes called the FOIL rule: "Firsts, Outers, Inners, Lasts"

$\left(\textcolor{b l u e}{d} \textcolor{red}{- 1}\right) \left(5 d - 4\right)$

$= \textcolor{b l u e}{d} \left(5 d - 4\right) \textcolor{red}{- 1} \left(5 d - 4\right)$

$= \textcolor{b l u e}{5 {d}^{2} - 4 d} \textcolor{red}{- 5 d + 4} \text{ } \leftarrow$ collect the like terms

$= 5 {d}^{2} - 9 d + 4 \text{ } \leftarrow$ this is the product.

(It is a quadratic trinomial )